OBJECTIVE: To assess the effects on patients, clinicians, and the healthcare system of interventions before consultations to help patients or their representatives gather information in consultations by question asking. DESIGN: Systematic review with meta-analysis. DATA SOURCES: Electronic literature searches of seven databases and hand searching of one journal and bibliographies of relevant articles. Review methods Inclusion criteria included randomised controlled trials. MAIN OUTCOME MEASURES: Primary outcomes were question asking; patients' anxiety, knowledge, and satisfaction; and length of consultation. RESULTS: 33 randomised trials of variable quality involving 8244 patients were identified. A few studies showed positive effects. Meta-analyses showed small and statistically significantly increases in question asking (standardised mean difference 0.27, 95% confidence interval 0.19 to 0.36) and patients' satisfaction (0.09, 0.03 to 0.16). Non-statistically significant changes occurred in patients' anxiety before consultations (weighted mean difference -1.56, -7.10 to 3.97), patients' anxiety after consultations (standardised mean difference -0.08, -0.22 to 0.06), patients' knowledge (-0.34, -0.94 to 0.25), and length of consultation (0.10, -0.05 to 0.25). Interventions comprising written materials had similar effects on question asking, consultation length, and patients' satisfaction as those comprising the coaching of patients. Interventions with additional training of clinicians had little further effect than those targeted at patients alone for patients' satisfaction and consultation length. CONCLUSIONS: Interventions for patients before consultations produce small benefits for patients. This may be because patients and clinicians have established behaviours in consultations that are difficult to change. Alternatively small increases in question asking may not be sufficient to make notable changes to other outcomes.